The present invention relates to an apparatus for controlling the monoplanar motion of an object, said apparatus comprising two opposite clamping means on either side of said object, one of which clamping means is operative to be moved between two extreme positions in a direction perpendicular to said plane of motion and with respect to the other clamping means, the one clamping means in one of the extreme positions thereof fixedly clamping said object between the two clamping means and in the other of said clamping positions allowing the movement of said object between said clamping means, and means for exerting a force on the one clamping means directed at least partially from or to, respectively, the other clamping means wherein said one clamping means is connected to one or more pieces of ferromagnetic and/or electrically conductive material.
The present invention furthermore relates to a case for a tape-like information carrier provided with such an apparatus for controlling the motion of the information carrier as well as to an apparatus for reading, writing or erasing information on a tape-like carrier to be used in combination with such a case.
An apparatus of the type indicated above for controlling the monoplanar motion of an object is known among others from the German Patent Specification No. 420,302. This patent specification discloses a film projector in which the film to be projected is guided between two windows. If the electromagnet coupled to one of the windows is not energized, the two windows are spaced at some distance with respect to each other and the film strip to be projected may pass freely between the windows. Upon energization of the electromagnet the windows are pressed again each other and the film strip will be clamped therebetween.
A similar apparatus is also known from the Netherlands Patent Application No. 66.09173. This patent application describes an apparatus in which an information carrying tape may be read. This apparatus includes one or more brake shoes which are pressed against the tape at an almost constant force by means of a leaf spring. If the tape has to be stopped the force at which the brake shoes are pressed against the tape is suddenly increased by energizing an electromagnet.
In accordance with the two literature references discussed above clamping means are pressed against a moving object or a pressing force already present is increased by the application of an (electromagnetic field. It is also possible, however, that there are provided means, permanently exerting a force on the clamping means whereby said clamping means are pressed against a moving object and that upon the application of an (electromagnetic field this force is compensated completely or partially.
Many information carriers are very sensitive to dust. The drawback of the above discussed apparatuses is that they are not of dustproof character and that the information carrier therein will consequently be subject to damage caused by dust.